Connecting with PostgreSQL 9.1 using the Ubuntu machine user and peer authentication method

Hello,

I want to connect to my local installation of PostgreSQL 9.1 using my
machine user (who is vagrant). So, after reading PostgreSQL documentation,
I thought I just needed to:

1. Add username map in pg_ident.conf:

# MAPNAME SYSTEM-USERNAME PG-USERNAME

vp vagrant postgres

2. Using the map in pg_hba.conf

# TYPE DATABASE USER ADDRESS METHOD

local all all
peer map=vp

But I'm getting the error

sql: FATAL: Peer authentication failed for user "vagrant"

If I try to connect to my server using psql.

I guess I'm misunderstanding the PostgreSQL manual. But, how could I get
what I need? (locally connect with the user vagrant like if it was the
postgres user)

Many thanks in advance (and sorry for the cross-posting. I asked this in
serverfault too, but I think this is the right place)

--
Jorge Arevalo

http://about.me/jorgeas80